The Detection of Structural Defects in GaAs by Electrochemical Etching

Abstract

Two methods of anodically etching n-GaAs have been investigated. Sub-sequently they have been used to detect crystallographic defects present in bulk-grown, single crystal material. The first method provides topographical featuring of the semiconductor anode. The selective discrimination of defects achieved via this controlled electrochemical technique is superior to that ob-tainable from standard chemical etchants. The second dissolution regime, in which an interracial oxide layer is continuously present, permits smooth, featureless removal of material. Thus a simple two-stage anodization procedure has allowed the damage characteristic of the Beilby layer to be probed. There-after, a total, smooth removal of this damaged surface layer permits identifi-cation of bulk crystallographic defects---dislocation structures well known in GaAs require the dissolution of only 0.5 ~m. Analysis of the semiconductor electrode condition in the electrolytes used for etching has yielded model results. Such analyses have enabled the relationship between the electrical